When replacing the exhaust parts (manifolds, risers, elbows) on your marine engine, the best way to make sure you find the proper replacements is to look at your current exhaust parts and write down the casting numbers from each. These casting numbers are often directly correlated with the part number, though in some cases there are extraneous casting numbers as well. Write down any and all, as you may need to search for each set to find the right replacement.
In some cases the casting numbers are on the engine side of the part, or up against the valve covers/head, making it difficult to see prior to removal. Try using a flashlight and extendible inspection mirror to get a better look. You can also sometimes carefully lower a smartphone and take a flash picture. There are some cases where the manifold must be removed prior to being able to ID it. Keep in mind that once removed it should not be reinstalled without cleaning mating surfaces and replacing gaskets.
With the casting numbers handy, you can try the Sierra SONAR tool, which matches OEM and aftermarket part numbers to Sierra parts. This tool also allows using engine make, model, year, and serial number to find parts, if you were unable to get casting numbers.
If you have a Mercury (MerCruiser) engine, you can also try the official Mercury Parts Express site, which will take your Mercury serial number and provide parts breakdowns and diagrams. These Mercury part numbers can then be used to find Sierra aftermarket replacements, if you wish.
With an OEM, Sierra, or other aftermarket part number, you can also do a search with us to see if we stock it.